Ofcom has released a series of maps on the UK's communications infrastructure, which reveal large regions of the country have poor superfast broadband coverage and 3G mobile access.
The maps are part of the regulator's first report on the UK's communications infrastructure, which it is required to submit to the government every three years.
Around 73% of premises and 13% of the UK's landmass can receive a signal outdoors from all five 3G networks, with lower coverage in less densely populated areas. This means that approximately 7.7 million UK premises do not have a choice of all five 3G mobile networks.
Some 97% of premises and 66% of the UK landmass can receive a 2G signal outdoors from all four 2G networks. This means that approximately 900,000 UK premises do not have a choice of all four 2G mobile networks.
But the maps show that superfast broadband speeds remain patchy outside of the country's main cites and Northern Ireland, with good 3G mobile coverage almost exclusively confined to London.
Each of the 200 areas of the UK has been ranked according to a score given for coverage and colour-coded (green ranking highest and red lowest). The information was compiled using data supplied by communications providers.
The maps follow government commitments to roll out superfast broadband to 90% of people in each local authority area. Superfast broadband services are generally considered to be those that run at over 24Mbps.
The government recently announced £363m in investment to improve broadband speeds in homes and businesses in England and Scotland, and committed £150m to improving mobile phone coverage.
Ofcom said it is working with the government to consider how to use the £150m it has allocated to help address mobile "not-spots".
Rob Bamforth, analyst at Quocirca, said it was imperative for the UK to improve its mobile coverage. "From a business perspective it's not good enough if you can't get a signal, particularly as the need for connectivity is increasing with remote working. This is obviously something we need to improve, otherwise it will put us at an economic disadvantage," he said.
Mathew Howett, analyst at Ovum, said the regulator's exercise was a useful in measuring the government's progress toward its broadband commitments, but ongoing monitoring would need to take place in between the three-year reports.
"One of the interesting things from this report is that fixed line is still seen as the number one means of accessing the internet for consumers and business users," he said.
Howett said the recent revision of BT's pole and duct prices is likely to lead to more activity in the bidding process for the government's broadband roll-out funds. "It's important to get things like that right first. BT is very significant - it's likely to make up the bulk of [broadband] roll-out," he said.